1. Field of the Invention
The present invention relates generally to a bicycle rim and, more particularly, to a bicycle rim having an inner periphery which has a non-constant diameter.
2. Description of the Related Art
Bicycling is becoming an increasingly more popular form of recreation as well as a means of transportation. One component of the bicycle that has been extensively redesigned is the bicycle wheel. Bicycle wheels are constantly being redesigned to be strong, lightweight and more aerodynamic in design as well as to be simple to manufacture and assemble.
U.S. Pat. No. 5,975,645 discloses a bicycle wheel which has good impact properties and increased durability. In one embodiment, the rim comprises a two piece rim having a carbon fiber based body portion having bulbous sidewalls capable of flexing in response to radially directed forces, and a tire engaging, hoop-like rim made from aluminum. The rim includes a pair of parallel braking surfaces. In the preferred embodiment, the convex curved sides of the wheel, in transverse cross section, are wider than the braking surfaces and intersect the braking surfaces at an angle of less than about 175 degrees.
In this known structure, the rim has a constant inner diameter and outer diameter so that the weight of each part of the rim is constant. The rim can not provide an extra moment of inertia while it is rotating.
The present invention is, therefore, intended to obviate or at least alleviate the problems encountered in the prior art.